This invention relates to a press-packed semiconductor device comprising high-power modules, such as transistors and thyristors.
An example of a conventional high-power semiconductor module is a transistor module as shown in FIG. 1. In FIG. 1, numeral 1 denotes a first transistor composite comprising a power transistor 11 and a diode 12, and numeral 2 represents a second transistor composite comprising a power transistor 13 and a diode 14. These first and second transistor composites 1, 2 are commonly connected to a metal substrate 17 through insulation substrates 15 and 16, respectively. The first and second transistor composites 1, 2 are housed in a package 18. A collector electrode terminal 19 of the first transistor composite 1, a collector electrode terminal 21 of the second transistor composite 2, which is coupled to an emitter electrode terminal 20 of the first transistor composite 1, and an emitter electrode terminal 22 of the second transitor composite 2 are arranged to extend outside of the package 18 on the top side thereof.
This arrangement provides easy assembling of the transistor module into an electric device and reduces the space necessary for installation, thus lightening the electric device.
The conventional transistor module, however, has the following drawbacks. Connection lines are bonded or soldered to the emitter electrodes and the collector electrodes of the first and second transistor composites 1 and 2. With a transistor module of a large current, e.g., above 100 A, such a connection causes current to concentrate on the bonded or soldered sections. This results in thermal distortion or thermal fatigue, making it difficult to provide a desirable high-power transistor module. Further, if the bonded or soldered sections are damaged by over-current, a sort of explosion may occur, namely, melted silicon may spout out from the package 18. Furthermore, because the metal substrate 17, package 18 and electrode terminals extending outside the package are simultaneously sealed by adhesive resin, a crack may easily occur due to the difference in the thermal expansion coefficients of the individual materials, impeding a proper sealing.